1. Field of the Invention
This invention relates to a side knock-type ball point pen in which a writing tip is adapted to be projected out of a ball point pen barrel by operating actuator means which is received in an opening portion formed in a portion of a peripheral wall of the ball point pen barrel.
2. Description of the Prior Art
Hitherto, there have been proposed rear end knock-type ball point pens and side slide-type ball point pens. However, a side knock-type ball point pen is not proposed yet. An example of the side slide-type ball point pens is disclosed in Japanese Utility Model Application which was published under Publication No. 32394/1994 on Aug. 24, 1994.
Referring now to FIG. 1, the conventional side slide-type ball point pen will be discussed in order to facilitate understanding of the present invention. The conventional side slide-type ball point pen includes a barrel 1, a head section 2 attached to a front end of the barrel 1, a refill 4 axially movably received in the barrel 1, a cam mechanism 5 for keeping a writing tip 4a of the refill 4 projected out of the head section 2 in use of the ball point pen, the cam mechanism 5 provided in a portion of an interior of the barrel 1 which positionally corresponds to a portion of the barrel 1 which is to be gripped by a user in use, and a slide plate 6 slidably received in an elongate hole 7 which is formed in a portion of a peripheral wall of the barrel 1, the slide plate 6 coupled to the cam mechanism 5. In the conventional ball point pen, the writing tip 4a of the refill 4 is projected out of the head section 2 by causing the slide plate 6 to be slid along the elongate hole 7 and kept projected out of the head section 2 by the cam mechanism 5.
In the conventional ball point pen, the cam mechanism which is complex in construction is disposed at the portion of the interior of the barrel 1 which positionally corresponds to the portion of the barrel 1 which is to be gripped by the user, so that the portion of the barrel 1 which is to be gripped by the user is inevitably fat. This causes the user to be fatigued in use of the ball point pen and causes an appearance of the ball point pen to be unshapely. In addition, since the cam mechanism 5 is complex in construction, it takes a lot of labor to incorporate the cam mechanism 5 into the barrel 1. Therefore, manufacturing cost of the ball point pen rises.